In a communication network, data such as user subscription information, authentication information and dynamic information (for example, home location) is stored in an HLR. With the continuous development of networks and services, the HLR evolves to a user data storage network with a large capacity, a distributed mode, high reliability, a separated architecture, a uniform data model and an open interface. Therefore, the HLR no longer presents in the physical form of a single system; instead, it presents as a network having a layered architecture with different functions, which is referred to as “distributed HLR system” in the industry.
As shown in FIG. 1, a distributed HLR system may be consisted of a plurality of user database devices and a plurality of HLR front ends. Where, the user database devices are used to store user data, and the HLR front ends are used to accomplish the conversion from an Mobile Application Part (MAP) Protocol to an Internal Standard Protocol. In order to improve the overall reliability of the system, a service system, such as MSC, Serving GPRS Support Node (SGSN) and Service Control Point (SCP), interacts with an HLR front end, and the HLR front end interacts with a user database device; a plurality of user database devices in a distributed HLR system store the same user data and synchronize the user data in real time so as to improve the security of the data; a plurality of devices in the distributed HLR system may be geographically widely deployed based on the IP bearer, so that they have the geographic disaster recovery capability.
At present, in a mobile communication network, a distributed HLR system employs the application mode as shown in FIG. 2. A distributed HLR system provides services to users in a plurality of signaling areas; in each signaling area, an HLR front end of the distributed HLR system is set proximately with a Signaling Transfer Point (STP) device and an MSC to reduce the link construction; the STP in each signaling area is responsible for routing an MAP signaling between different signaling areas according to the number range.
In the above application mode, it is hypothesized that a user A with the number of 1390011001 in a signaling area 1 calls a user B with the number of 1390012001 in a signaling area 2 via an MSC 1, the procedure of fetching a roaming number of a callee from a visited MSC is as shown in FIG. 3, which includes the following processes.
S301: The MSC 1 initiates an MAP request message for Send Routing Information (SRI) via a proximate HLR front end (for example, an HLR front end A).
S302: A user database device initiates an MAP operating process for Provide Roaming Number (PRN) via the HLR front end A according to a registration MSC number of the user B (which is MSC 2 herein).
S303: The HLR front end A generally selects a proximate STP 1 for the routing of a PRN request message to the MSC 2.
S304: The MSC 2 returns the roaming number of the user B in a PRN response message after receiving the PRN request message (no matter whether the user B registers in an MSC of the home network or registers in an MSC of the roaming network, the network allocates a roaming number to the user B).
The PRN response message reaches the user database device via the STP 2, the STP 1 and the HLR front end A.
S305: The user database device feeds back the roaming number of the user B to the MSC 1 via an SRI response message.
S306: The MSC 1 initiates to the MSC 2 a call to the user B according to the roaming number of the user B.
It can be seen from the above procedure that, in the prior art, when fetching the roaming number of the callee from the visited MSC (i.e., determining the routing of the callee according to the roaming number of the callee), the distributed HLR system selects the HLR front end that functions as the entrance of the SRI request message as the exit of the PRN request message. The inventors of the present invention find that, in such a method for fetching the roaming number of the callee from the visited MSC, the routing of the PRN message is circuitous, which increases the load of the STP interfaces and links of the signaling network, thus wasting the network resources and bringing larger time delay of a service.